1. Field of the Invention
The present invention relates generally to recording apparatus, and, more particularly, to an apparatus for determining and recording a surface profile of a metallic workpiece.
2. Description of the Prior Art
In the casting of molten metal by continuous casting techniques, close attention is paid to the profiles of the shapes formed by the casting process. In the particular instance in which slabs are produced by the continuous caster, uniform flatness of the slab surfaces is desired. When the surfaces of the slabs are not flat, subsequent processing is required in order to flatten the surfaces. Such processing usually involves grinding operations, which reduces the yield of the slab, and increases production time and expense.
Because the molten metal located in the center portions of the slabs cool at a slower rate than side and end portions of the slabs, slabs produced by the continuous casters occasionally contain "guttered" areas running in lengthwise directions through the slabs. In order to obtain quantitative data to determine casting conditions which minimize such gutters (and, therefore increase the flatness of the slabs), surface profiles of the finished slabs are desired.
One method of quantitatively determining the surface profile of a workpiece requires that a portion of the slab be cut and transported to a remote location whereat the slab portion is cut into sections to provide a cross section of the slab, the surface of which may be analyzed to obtain a surface profile. This is a time consuming and expensive process which cannot be performed during on-line production.
Because such a procedure is so time consuming, a quicker procedure by which a surface profile of the slab is obtained by a qualitative means is more frequently utilized. The profile is obtained by a process known as "guttering". In this process, a long straight edge rule is placed across the top surface of the slab such that the rule traverses opposite sides of the slab. An observer then merely estimates the depth of the guttered areas running along the length of the slab. Such a process is oftentimes quite inaccurate and is of limited precision.
It is therefore an object of the present invention to provide a means for quantitatively determining the surface profile of a metallic workpiece, such as a steel slab.
It is a further object of the present invention to provide a non-invasive means for quantitatively determining both the top and the bottom surface profiles of a metallic workpiece during on-line production of the workpiece.